I've come across Railway Emergency (Group) Calls on the GSM-R radio equipment in various places (principally in RAIB reports) and have seen some training videos for them on YouTube. I've often wondered: how often are they actually used? Could a signaller manage to go his entire career without receiving one? Or do they happen fairly regularly? Presumably they are unusual enough that receiving one as a signaller is still a bit of a 'heart stopping' moment?